JP5695276B2 - Use of polyamic acid, polyimide, polyamic acid solution, and polyimide - Google Patents

Description

  The present invention relates to a polyamic acid, a polyimide, and a polyamic acid solution. The present invention further includes an electronic device material using polyimide, a TFT substrate, a flexible display substrate, a color filter, a printed material, an optical material, a liquid crystal display device, an organic EL, an electronic display such as electronic paper, a 3-D display, and a solar. The present invention relates to an alternative material for a battery, a touch panel, a transparent conductive film substrate, and a portion where glass is currently used.

  In recent years, with rapid advances in displays such as liquid crystal, organic EL, and electronic paper, and electronics such as solar cells and touch panels, devices are required to be thinner and lighter, and more flexible. Therefore, in place of the glass substrate used in these devices, a plastic film substrate that can be made thin, light, and flexible has been studied.

  In these devices, various electronic elements such as thin film transistors and transparent electrodes are formed on a substrate, and a high-temperature process is required to form these electronic elements. Therefore, the plastic film substrate is required to have sufficient heat resistance that can be adapted to a high temperature process. In addition, when these electronic elements made of an inorganic material are formed on a film, the film is warped after the formation of the inorganic element due to the difference in linear thermal expansion coefficient between the inorganic material and the film, and further, the inorganic element is destroyed. There was a fear. For this reason, a material having a linear thermal expansion coefficient equivalent to that of an inorganic material while having heat resistance has been desired.

  Further, when light emitted from a display element (liquid crystal, organic EL, etc.) is emitted through a plastic film substrate (for example, bottom emission type organic EL, etc.), the plastic film substrate needs to be transparent. Become. In particular, the light transmittance is required to be high in a wavelength region of 400 nm or less that is a visible light region. When light passes through a retardation film or a polarizing plate (for example, a liquid crystal display, a touch panel, etc.), the plastic film substrate is required to have high optical isotropy in addition to transparency. .

  The manufacturing process of these devices is divided into a batch type and a roll-to-roll type. When using a roll-to-roll fabrication process, new equipment is required and several problems due to rotation and contact must be overcome. On the other hand, the batch type is a process in which a coating resin solution is applied on a glass substrate, dried, a substrate is formed and then peeled off. Therefore, the batch type is advantageous in terms of cost because it can use the current glass substrate process equipment such as TFT.

  From such a background, development of a material that can be applied to an existing batch process, has excellent heat resistance, low thermal expansion, transparency, and low birefringence is strongly desired.

  As a material satisfying the above requirements, a polyimide material known as a material having excellent heat resistance has been studied. In order to obtain a polyimide having high transparency and low thermal expansion, a monomer having a rigid structure or an alicyclic monomer is generally used (Patent Documents 1 and 2). On the other hand, it is known that polyimide containing a fluorene structure exhibits heat resistance and low water absorption (Patent Document 3).

Japanese Patent Publication “JP 2002-161136 A (published June 4, 2002)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2012-41530 (published March 1, 2012)” Japanese Patent Publication “JP 2009-079165 (April 16, 2009)”

  Although the polyimide described in Patent Document 1 is excellent in heat resistance and low thermal expansion, the transparency is not sufficient, and there is no description regarding birefringence. Moreover, although the polyimide of patent document 2 is excellent in transparency and a low thermal expansion characteristic, there is no description regarding birefringence. The polyimide containing a fluorene structure described in Patent Document 3 is excellent in heat resistance and low thermal expansion, but has insufficient transparency and no description on birefringence.

  The present invention has been accomplished in view of the above circumstances, and is to obtain polyimide having excellent heat resistance, low thermal expansion, transparency, low birefringence, and polyamic acid as a precursor thereof. Objective. Furthermore, it aims at providing the product or member with a high request | requirement of heat resistance and transparency using the said polyimide and polyamic acid. In particular, it is an object of the present invention to provide a product and a member that are applied to applications in which the polyimide and the polyamic acid of the present invention are formed on an inorganic surface such as glass, metal, metal oxide, and single crystal silicon.

  The inventors of the present invention introduced a rigid structure and an alicyclic structure in the skeleton in order to obtain a polyimide having excellent heat resistance, low thermal expansion, and transparency, which are the above-mentioned problems, and exhibiting low birefringence. Furthermore, it has been found that it is effective to use a monomer having a fluorene skeleton in combination.

  That is, the polyamic acid according to the present invention is characterized by containing a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2):

R ₁ and R ₂ are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, which may be the same or different, and A in the general formula (2) is a formula The component derived from acid dianhydride, which is any one selected from the structural unit represented by (3), the structural unit represented by formula (4), and the structural unit represented by formula (5) It is.

  In addition, the polyimide according to the present invention is characterized by containing a structural unit represented by the general formula (6) and a structural unit represented by the general formula (7):

  R1 and R2 are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, which may be the same or different, and A in the general formula (7) is represented by the formula (3 ), A structural unit represented by formula (4), and a structural unit represented by formula (5), which is a component derived from acid dianhydride. .

  The polyimide according to the present invention and the polyimide produced using the polyamic acid according to the present invention have low birefringence in addition to heat resistance, low thermal expansibility, and transparency. Therefore, the polyimide according to the present invention and the polyamic acid according to the present invention are used as a film or a coating film for a member required to have low birefringence in addition to heat resistance, low thermal expansion and transparency. Is preferred.

It is a figure which shows typically the mode of peeling or a float between a polyimide and a support body when a polyamic acid solution is apply | coated and imidized on a support body.

  The present invention is described in detail below.

  The polyamic acid produced by the present invention includes a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2).

Here, R ₁ and R ₂ in the formula are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, and these may be the same or different. From the viewpoint of expression of low thermal expansion, R ₁ and R ₂ are preferably each independently a hydrogen atom or an alkyl group, and from the viewpoint of heat resistance, R ₁ and R ₂ are preferably a hydrogen atom. Particularly preferred. That is, the structural unit represented by the formula (1) is a polyamic acid represented by the formula (8) obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 1,4-cyclohexanediamine. Most preferably, it is a structural unit.

  A in the general formula (2) is a structural unit containing a fluorene skeleton, and from the viewpoint of reducing birefringence, the structural unit represented by the formula (3), the structural unit represented by the formula (4), and One is preferably selected from the structural units represented by the formula (5), and the structural unit represented by the formula (3) is particularly preferable from the viewpoint of heat resistance.

  That is, the structural unit represented by the formula (2) includes the structural unit represented by the following formula (9), the structural unit represented by the following formula (12), and the structural unit represented by the following formula (13). It is preferable to select one, and from the viewpoint of heat resistance, the structural unit represented by the formula (9) is most preferable.

  From the viewpoint of improving the heat resistance, low thermal expansion, transparency, and low birefringence of the resulting polyimide, the constitutional unit represented by the general formula (1) and the constitution represented by the general formula (2) in the polyamic acid. The total number of moles with the unit is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more with respect to the number of moles of the polyamic acid. Here, the number of moles of the polyamic acid is the number of moles of the structural units derived from all diamines constituting the polyamic acid or the number of moles of structural units derived from all the acid dianhydrides constituting the polyamic acid.

  The polyamic acid of the present invention is characterized by containing a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2), and is represented by the formula (1) of the present invention. In the polyamic acid containing the structural unit and the structural unit represented by the formula (2), the number of moles of the structural unit represented by the formula (1) / the number of moles of the structural unit represented by the formula (2) The molar ratio is preferably 30/70 or more, and more preferably 50/50 or more, from the viewpoint of expression of low thermal expansion. In addition, the molar ratio represented by the number of moles of the structural unit represented by the formula (1) / the number of moles of the structural unit represented by the formula (2) is a low birefringence viewpoint and a polyamide on the support. From the viewpoint of adhesion between the support and the polyimide when the acid solution is applied and imidized, it is preferably 99/1 or less, more preferably 98/2 or less, and 97/3 or less. Is more preferably 95/5 or less, and most preferably 80/20 or less.

  The polyamic acid of the present invention is characterized by containing a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2). As described above, the general formula (1) The structural unit represented by the formula (8) is particularly preferred, and the structural unit represented by the general formula (2) is particularly preferably a structural unit represented by the formula (9). In the polyamic acid containing the structural unit represented by the formula (8) and the structural unit represented by the formula (9), the number of moles of the structural unit represented by the formula (8) / the formula (9) The molar ratio represented by the number of moles of the structural unit is preferably 30/70 or more, and more preferably 50/50 or more, from the viewpoint of expression of low thermal expansion. In addition, the molar ratio represented by the number of moles of the structural unit represented by the formula (8) / the number of moles of the structural unit represented by the formula (9) is a low birefringence viewpoint and a polyamide on the support. From the viewpoint of adhesion between the support and the polyimide when the acid solution is applied and imidized, it is preferably 99/1 or less, more preferably 98/2 or less, and 97/3 or less. Is more preferably 95/5 or less, and most preferably 80/20 or less.

  In particular, in a batch type device manufacturing process in which a polyamic acid solution is applied onto a support such as glass, heated to imidize, an electronic element or the like is formed to form a substrate, and then peeled, the support and polyimide It is more preferable that the adhesion between the two is good. The term “adhesion” as used herein does not mean adhesion strength, but means the degree of peeling or floating between the polyimide and the support when a polyamic acid solution is applied onto a support such as glass and imidized. . That is, it can be said that the smaller the peeling or floating between the polyimide and the support, the better the adhesion. Such peeling or floating is formed as foamy peeling or floating between the support and the polyimide when the polyamic acid solution is applied onto a support such as glass and imidized. Hereinafter, peeling or floating between the polyimide and the support will be described with reference to FIG. That is, FIG. 1 shows that, for example, when a polyamic acid solution 2 is applied to a support 1 such as glass and heated to imidize the polyamic acid, peeling or floating between the polyimide and the support is formed. The state of being done is shown schematically. When the polyamic acid solution 2 is applied to a support 1 such as glass ((a) in FIG. 1) and heated, imidization of the polyamic acid starts. As the imidization proceeds, the water and / or organic solvent of the polyamic acid solution 2 exits from the polyamic acid being imidized to the outside as indicated by arrows in FIG. However, at this time, a part of water and / or organic solvent is not discharged from the polyamic acid during imidation as shown by the arrow marked with x in FIG. Stays with the polyamic acid inside. And the water and / or organic solvent which remained between this support body and the polyamic acid in imidation is foamy between the obtained polyimide and support body, as shown in (c) of FIG. To form peeling or floating. The water and / or the organic solvent is then discharged from the foam-like peeling or floating through the polyimide or the support, and finally, the foamed portion of the peeling or floating becomes a space composed of air. By reducing the formation of such peeling or floating, after forming a substrate by forming an electronic element or the like on a polyimide film on a support, the polyimide substrate on which the electronic element or the like is formed is peeled from the support. In addition, an electronic element or the like can be formed or mounted more accurately. In particular, in a thinned or miniaturized device, even if fine peeling or floating has a great influence on formation or mounting of an electronic element or the like, reduction of the peeling or floating is important.

  Preferably, the molar ratio represented by the number of moles of the structural unit represented by formula (1) / the number of moles of the structural unit represented by formula (2), more preferably represented by formula (8). When the molar ratio represented by the number of moles of the structural unit / number of moles of the structural unit represented by the formula (9) is 99/1 or less, the adhesion between the support and the polyimide is improved. Therefore, the molar ratio represented by the number of moles of the structural unit represented by formula (1) / the number of moles of the structural unit represented by formula (2), more preferably the structural unit represented by formula (8) When the molar ratio represented by the number of moles of the structural unit represented by the formula (9) is 99/1 or less, low birefringence and a polyamic acid solution are coated on the support to form an imide. In this case, excellent adhesion between the support and the polyimide is realized.

Among them, the viewpoint of satisfying low birefringence and excellent adhesion between the support and the polyimide when imidizing by applying a polyamic acid solution on the support, and achieving particularly low thermal expansion From
Number of moles of structural unit represented by formula (2) / (number of moles of structural unit represented by formula (1) + number of moles of structural unit represented by formula (2)),
Is more preferably 0.01 or more and less than 0.05, and further preferably 0.02 or more and less than 0.05.
From the same viewpoint, the number of moles of the structural unit represented by formula (9) / (number of moles of the structural unit represented by formula (8) + number of moles of the structural unit represented by formula (9)).
Is more preferably 0.01 or more and less than 0.05, and further preferably 0.02 or more and less than 0.05.

  The polyimide produced by the present invention includes a structural unit represented by the general formula (6) and a structural unit represented by the general formula (7).

R1, R2 and A in the formula are respectively the same as _R 1, _{R 2} and A in the general formula (1) and general formula (2). That is, the general formula (6) is a polyimide constituent unit represented by the formula (10) obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 1,4-cyclohexanediamine. Most preferred.

  A in the general formula (7) is a structural unit containing a fluorene skeleton, and from the viewpoint of reducing birefringence, the structural unit represented by the formula (3), the structural unit represented by (4), and (5 Is preferably selected from the structural units represented by formula (3), and is particularly preferably a structural unit represented by the formula (3) from the viewpoint of heat resistance. That is, the structural unit represented by the general formula (7) includes the structural unit represented by the following formula (11), the structural unit represented by the following formula (14), and the structural unit represented by the following formula (15). One unit is preferably selected, and from the viewpoint of heat resistance, the structural unit represented by the formula (11) is most preferable.

  From the viewpoint of improving heat resistance, low thermal expansion, transparency, and low birefringence, the total of the structural unit represented by the general formula (6) and the structural unit represented by the general formula (7) in polyimide. Is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more with respect to the number of moles of polyimide. Here, the number of moles of polyimide is the number of moles of all diamine-derived constituent units constituting polyimide or the number of moles of all acid dianhydride-derived constituent units constituting polyimide.

  The polyimide of the present invention is characterized by containing a structural unit represented by the general formula (6) and a structural unit represented by the general formula (7), and is represented by the formula (6) of the present invention. In the polyimide containing the structural unit and the structural unit represented by the formula (7), the number of moles of the structural unit represented by the formula (6) / the number of moles of the structural unit represented by the formula (7). The molar ratio is preferably 30/70 or more, and more preferably 50/50 or more, from the viewpoint of expression of low thermal expansion. In addition, the molar ratio represented by the number of moles of the structural unit represented by the formula (6) / the number of moles of the structural unit represented by the formula (7) is a low birefringence viewpoint and a polyamide on the support. From the viewpoint of adhesion between the support and the polyimide when the acid solution is applied and imidized, it is preferably 99/1 or less, more preferably 98/2 or less, and 97/3 or less. Is more preferably 95/5 or less, and most preferably 80/20 or less.

  The polyimide of the present invention is characterized by containing a structural unit represented by the general formula (6) and a structural unit represented by the general formula (7). It is particularly preferable that the structural unit represented is a structural unit represented by the formula (10), and the structural unit represented by the general formula (7) is a structural unit represented by the formula (11). In the polyimide containing the structural unit represented by the formula (10) and the structural unit represented by the formula (11) of the present invention, the number of moles of the structural unit represented by the formula (10) / the formula (11) The molar ratio represented by the number of moles of structural units is preferably 30/70 or more, and more preferably 50/50 or more, from the viewpoint of expression of low thermal expansion. In addition, the molar ratio represented by the number of moles of the structural unit represented by the formula (10) / the number of moles of the structural unit represented by the formula (11) is a low birefringence viewpoint and a polyamide on the support. From the viewpoint of adhesion between the support and the polyimide when the acid solution is applied and imidized, it is preferably 99/1 or less, more preferably 98/2 or less, and 97/3 or less. Is more preferably 95/5 or less, and most preferably 80/20 or less.

Among them, the viewpoint of satisfying low birefringence and excellent adhesion between the support and the polyimide when imidizing by applying a polyamic acid solution on the support, and achieving particularly low thermal expansion From
Number of moles of structural unit represented by formula (7) / (number of moles of structural unit represented by formula (6) + number of moles of structural unit represented by formula (7)),
Is more preferably 0.01 or more and less than 0.05, and further preferably 0.02 or more and less than 0.05.
From the same viewpoint, the number of moles of the structural unit represented by formula (11) / (number of moles of the structural unit represented by formula (10) + number of moles of the structural unit represented by formula (11)).
Is more preferably 0.01 or more and less than 0.05, and further preferably 0.02 or more and less than 0.05.

  The polyimide of this invention can be obtained by imidating the polyamic acid containing the structural unit represented by General formula (1) and the structural unit represented by General formula (2). The polyimide of the present invention may be synthesized from a generally known precursor such as a polyamic acid ester, or may be produced without going through the precursor.

  The polyamic acid of the present invention can be synthesized by a known general method, and can be obtained by reacting diamine and tetracarboxylic dianhydride in an organic solvent. Specifically, for example, in an inert atmosphere such as argon or nitrogen, the diamine is dissolved in an organic solvent or dispersed in a slurry to obtain a diamine solution. On the other hand, tetracarboxylic dianhydride may be added to the diamine solution after being dissolved or dispersed in an organic solvent or in a solid state.

  When synthesizing a polyamic acid using a diamine and a tetracarboxylic dianhydride, the number of moles of the total amount of one or more diamine components and the number of moles of the total amount of one or more tetracarboxylic dianhydride components are substantially By adjusting to an equimolar ratio, a polyamic acid copolymer can be arbitrarily obtained. Moreover, the polyamic acid containing several tetracarboxylic dianhydride and diamine can also be obtained by blending 2 types of polyamic acids. The temperature conditions for the reaction between the diamine and tetracarboxylic dianhydride, that is, the polyamic acid synthesis reaction, are not particularly limited. When an alicyclic diamine is used, salt formation often occurs. Therefore, the temperature of the polyamic acid synthesis reaction may be set in the range of 50 ° C. to 150 ° C. as necessary, and the salt dissolves and the polymerization reaction proceeds. If it starts, in order to suppress the molecular weight fall of a polyamic acid, it is preferable that the temperature of the synthesis reaction of a polyamic acid shall be 80 degrees C or less, and it is more preferable to set it as 0 to 50 degreeC. Moreover, what is necessary is just to set reaction time arbitrarily in the range of 10 minutes-30 hours.

  Furthermore, the organic solvent used for the synthesis reaction of the polyamic acid is not particularly limited as long as it is an organic polar solvent. As the reaction between the diamine and tetracarboxylic dianhydride proceeds, polyamic acid is generated, and the viscosity of the reaction solution increases.

  The organic solvent used for the polymerization of the polyamic acid is preferably one that can dissolve the tetracarboxylic dianhydride and diamines to be used, and more preferably one that can dissolve the produced polyamic acid. . Examples of the organic solvent used in the above polyamic acid synthesis reaction include urea solvents such as tetramethylurea and N, N-dimethylethylurea, sulfoxides such as dimethylsulfoxide, diphenylsulfone, and tetramethylsulfone, and sulfone solvents. N, N-dimethylacetamide (DMAC), N, N-dimethylformamide (DMF), N, N′-diethylacetamide, N-methyl-2-pyrrolidone (NMP), ester solvents such as γ-butyrolactone, hexa Amide solvents such as methyl phosphate triamide, alkyl halide solvents such as chloroform and methylene chloride, aromatic hydrocarbon solvents such as benzene and toluene, phenol solvents such as phenol and cresol, and ketone solvents such as cyclopentanone Solvent, tetrahydrofura , 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, ether solvents such as p- cresol methyl ether. Usually, these solvents are used alone, but two or more kinds may be used in appropriate combination as required. In order to increase the solubility and reactivity of the polyamic acid, the organic solvent used for the polyamic acid synthesis reaction is preferably selected from amide solvents, ketone solvents, ester solvents, and ether solvents. Amide solvents such as DMF, DMAC and NMP are preferred.

  The polyimide of the present invention can be obtained by a known method, and its production method is not particularly limited. From the viewpoint of availability of monomers and ease of polymerization, the polyimide of the present invention is preferably obtained from polyamic acid which is a precursor thereof. A method for imidizing the above polyamic acid to obtain a polyimide using the polyamic acid will be described. Imidization is performed by dehydrating and ring-closing the polyamic acid. This dehydration ring closure can be performed by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. Moreover, imidation from a polyamic acid to a polyimide can take an arbitrary ratio of 1 to 100%. That is, a polyamic acid partially imidized may be synthesized. In this specification, a solution containing a polyamic acid and an organic solvent is referred to as a polyamic acid solution. Here, as the organic solvent contained in the polyamic acid solution, an organic solvent similar to the organic solvent used for the polyamic acid synthesis reaction can be used, and among them, an amide solvent, a ketone solvent, and an ester solvent. And an organic solvent selected from ether solvents can be used more preferably, and amide solvents such as DMF, DMAC, and NMP can be particularly preferably used. When polyamic acid is obtained by the above-described method, the synthesized reaction solution itself may be expressed as a polyamic acid solution.

  The dehydration ring closure may be performed by heating the polyamic acid. The method for heating the polyamic acid is not particularly limited. For example, the polyamic acid solution is cast or coated on a support such as a glass plate, a metal plate, or PET (polyethylene terephthalate), and then within a range of 80 ° C to 500 ° C. Heat treatment may be performed. Alternatively, the polyamic acid solution can be directly dehydrated and closed by placing the polyamic acid solution directly into a container that has been subjected to a release treatment such as coating with a fluororesin, and heating and drying the polyamic acid solution under reduced pressure. Polyimide can be obtained by dehydration ring closure of polyamic acid by such a method. In addition, although the heating time of each said process changes with the process amount and heating temperature of the polyamic acid solution which performs dehydration ring closure, generally it is performed in the range of 1 minute-5 hours after the processing temperature reaches the maximum temperature. It is preferable. Further, in order to shorten the heating time and develop the characteristics, an imidizing agent and / or a dehydration catalyst are added to the polyamic acid solution, and the polyamic acid solution to which the imidizing agent and / or the dehydration catalyst is added is treated as described above. May be imidized by heating.

  Although it does not specifically limit as said imidating agent, A tertiary amine can be used. As the tertiary amine, a heterocyclic tertiary amine is more preferable. Preferable specific examples of the heterocyclic tertiary amine include pyridine, picoline, quinoline, isoquinoline and the like. Specific examples of the dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and the like.

  As the addition amount of the imidizing agent and the dehydration catalyst, the imidizing agent is 0.5 to 5.0 times molar equivalent, more preferably 0.7 to 2.5 times molar equivalent, especially with respect to the amide group of the polyamic acid. Is preferably 0.8 to 2.0 times molar equivalent. Further, the dehydration catalyst is 0.5 to 10.0 times molar equivalent, more preferably 0.7 to 5.0 times molar equivalent, particularly 0.8 to 3.0 times molar equivalent, relative to the amide group of the polyamic acid. Is preferred. When the imidizing agent and / or dehydration catalyst is added to the polyamic acid solution, it may be added directly without being dissolved in the organic solvent, or a solution dissolved in the organic solvent may be added. In the method of adding directly without dissolving in an organic solvent, the reaction may proceed rapidly before the imidizing agent and / or dehydration catalyst diffuses, and a gel may be formed. More preferably, a solution obtained by dissolving the imidizing agent and / or dehydration catalyst in an organic solvent is mixed with the polyamic acid solution.

  The weight average molecular weight of the polyamic acid and polyimide of the present invention is preferably in the range of 10,000 or more and 500,000 or less, more preferably in the range of 20,000 to 300,000, depending on the use. Preferably, it is in the range of 30,000 to 200,000. If the weight average molecular weight is 10,000 or more, it becomes possible to use polyamic acid and polyimide as a coating film or film. On the other hand, when the weight average molecular weight is 500,000 or less, sufficient solubility in a solvent is exhibited, so that a coating film or film having a smooth surface and a uniform film thickness can be obtained from a polyamic acid solution described later.

  The molecular weight used here refers to a value in terms of polyethylene glycol by gel permeation chromatography (GPC).

  The polyimide of the present invention can be produced by applying a polyamic acid solution to a support and drying or heating. In this specification, the film-like polyimide obtained by the method described above may be expressed as a polyimide film. Here, the polyamic acid solution may be a partially imidized solution. Drying or heating may be performed under air, or may be performed under a nitrogen atmosphere. It is particularly preferable to dry or heat in a nitrogen atmosphere from the viewpoint of transparency.

  As the support on which the polyamic acid solution is applied, a glass substrate; a metal substrate such as SUS or a metal belt; a plastic film such as polyethylene terephthalate, polycarbonate, polyacrylate, polyethylene naphthalate, or triacetyl cellulose is used. It is not limited to. In order to adapt to the current batch type device manufacturing process, it is preferable to use a glass substrate.

  Regarding the drying temperature or heating temperature at the time of manufacturing the polyimide film, it is possible to select conditions suitable for the process, and there is no particular limitation as long as the characteristics are not affected.

  The transparency of polyimide is expressed by, for example, total light transmittance or haze according to JIS K7105-1981. When a polyimide film is used for the application of the present invention described later, the total light transmittance of the polyimide is preferably 80% or more, and more preferably 85% or more. The haze is preferably 2.0% or less, and more preferably 1.0% or less. In applications of the present invention, polyimide is required to have high transmittance in the entire wavelength range, but polyimide tends to absorb light on the short wavelength side, and the film itself is often colored yellow. For use in the application of the present invention, when the film thickness is 10 μm, the light transmittance at a wavelength of 400 nm is preferably 50% or more, more preferably 60% or more, and 70%. More preferably, it is larger. The light transmittance at a wavelength of 400 nm is measured by an ultraviolet-visible spectrophotometer. Thus, by giving transparency, a polyimide film can be used as transparent substrates, such as a glass alternative use.

  The polyimide of the present invention has low linear thermal expansion characteristics and dimensional stability before and after heating as film characteristics. For example, when these values are measured by thermomechanical analysis (TMA), TMA120C manufactured by Seiko Electronics Co., Ltd. is used (sample size: width 3 mm, length 10 mm, film thickness is measured, and the cross-sectional area of the film is calculated) When the temperature was raised from 10 ° C. to 340 ° C. at 10 ° C./min with a load of 3 gf, cooled to 10 ° C., and further heated to 340 ° C. at 10 ° C./min. A polyimide having a linear thermal expansion coefficient of 50 ppm / K or less, more preferably 40 ppm / K or less, in the range of 100 ° C. to 300 ° C., obtained from the amount of change in strain of the sample per unit temperature at 100 to 300 ° C. Can be obtained.

  The higher the glass transition temperature, the better from the viewpoint of heat resistance. Specifically, in differential scanning calorimetry (DSC) or dynamic viscoelasticity analysis (DMA), the glass transition temperature when measured at a temperature rising rate of 10 ° C./min is preferably 250 ° C. or higher. From the viewpoint of being able to cope with a high process temperature, it is more preferably 300 ° C. or higher.

When the optical properties of polyimide are used in the application of the present invention, it is preferable that the birefringence is small. Since polyimide is easily oriented in the plane, the difference in refractive index between the in-plane direction and the thickness direction (birefringence) is large. In particular, in the case of polyimide exhibiting low thermal expansion characteristics, the birefringence often increases. For use in the application of the present invention, when the in-plane refractive index is defined as nx, the smallest one is defined as ny, and the refractive index in the thickness direction is defined as nz,
nx-ny <0.0010 and (nx + ny) / 2-nz <0.160
Preferably satisfying
nx−ny <0.0010 and (nx + ny) /2−nz≦0.120
More preferably,
nx-ny <0.0010 and (nx + ny) / 2-nz <0.100
It is more preferable that nx−ny <0.0010 and (nx + ny) / 2−nz <0.050 because it is preferable that the optical isotropy is higher.
It is particularly preferable to satisfy Here, (nx + ny) / 2−nz represents the difference in refractive index between the in-plane direction and the thickness direction, that is, birefringence, and the lower this value, the better the optical isotropy. Here, nx-ny is more preferably less than 0.0002, and even more preferably less than 0.0001.

  The polyamic acid and polyimide according to the present invention may be used as they are for coating and molding processes for producing products and members as they are, but a laminate for further processing such as coating on a molded product formed into a film shape It can also be used as In order to provide a coating or molding process, the polyamic acid and polyimide are dissolved or dispersed in an organic solvent as necessary, and further, a light or thermosetting component, a non-polymerizable binder other than the polyamic acid and polyimide according to the present invention. A polyamic acid and a polyimide resin composition may be prepared by blending a resin and other components.

  In order to impart processing characteristics and various functionalities to the polyamic acid and polyimide according to the present invention, various other organic or inorganic low-molecular or high-molecular compounds may be blended. For example, dyes, surfactants, leveling agents, plasticizers, fine particles, sensitizers, and the like can be used. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, inorganic fine particles such as colloidal silica, carbon, and layered silicate, and these may have a porous or hollow structure. The function or form includes pigments, fillers, fibers, and the like.

  The polyamic acid and polyimide according to the present invention include the polyamic acid represented by the general formulas (1) and (2) or the polyimide represented by the formulas (6) and (7) with respect to the entire solid content of the composition. Usually, it is contained within the range of 60 to 99.9% by weight. In other words, the polyamic acid and the polyimide according to the present invention are represented by the polyamic acid containing the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2), or represented by the general formula (6). The polyimide containing the structural unit and the structural unit represented by the general formula (7) is usually contained within a range of 60 to 99.9% by weight with respect to the entire solid content of the composition. More preferably, the polyamic acid and the polyimide according to the present invention are a polyamic acid containing a structural unit represented by the formula (8) and a structural unit represented by the formula (9), or a general formula (10). The polyimide containing the structural unit represented and the structural unit represented by the general formula (11) is usually contained in the range of 60 to 99.9% by weight with respect to the entire solid content of the composition. 99.9% by weight means substantially all of them. Moreover, it is preferable that the mixture ratio of another arbitrary component is the range of 0.1 weight%-95 weight% with respect to the whole solid content of a polyimide. When the blending ratio is 0.1% by weight or more, the effect of adding the additive is easily exhibited. When the blending ratio is 95% by weight or less, the characteristics of the resin composition are easily reflected in the final product. In addition, solid content of a composition is all components other than an organic solvent, and a liquid monomer component is also contained in solid content.

  The polyimide film according to the present invention may have various inorganic thin films such as metal oxides and transparent electrodes formed on the surface thereof. The method for producing these inorganic thin films is not particularly limited, and examples thereof include PVD methods such as CVD, sputtering, vacuum deposition, and ion plating.

  The polyimide according to the present invention has low birefringence in addition to heat resistance, low thermal expansibility, and transparency, and also has good adhesion between the support and the polyimide, so these characteristics are effective. For example, printed products, color filters, flexible displays, optical films, liquid crystal display devices, organic EL, electronic paper and other image display devices, 3-D displays, touch panels, transparent conductive film substrates, or solar cells. It is preferably used, and more preferably an alternative material for the part where glass is currently used. That is, the polyamic acid containing the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) according to the present invention, preferably the structural unit represented by the general formula (1) is represented by the formula The structural unit represented by (8), wherein the structural unit represented by the general formula (2) is the structural unit represented by the formula (9), and the configuration represented by the general formula (6) The polyimide containing the unit and the structural unit represented by the general formula (7), preferably the structural unit represented by the formula (6) is the structural unit represented by the formula (10), and is represented by the formula (7). The polyimide whose structural unit is the structural unit represented by (11) can be suitably used particularly for substrates, image display devices, optical materials, and electronic device materials. This substrate refers to a TFT substrate, an ITO substrate, a flexible display substrate, or the like. This image display device refers to organic EL, electronic paper, a touch panel, and the like. This optical material refers to a color filter or the like. The polyimide of the present invention is also expected to be used as an antireflection film, hologram, optical member, building material or structure.

  In addition, the polyamic acid, polyimide and polyamic acid solution according to the present invention is a batch type in which a polyamic acid solution is applied on a support, imidized by heating, a substrate is formed by forming an electronic device or the like, and then peeled off. It can be suitably used for the device manufacturing process. Therefore, in the present invention, a method for producing an electronic device includes a substrate forming step of applying a polyamic acid solution on a support, heating to imidize, and forming an electronic element or the like on a polyimide film formed on the support Is also included. Moreover, the manufacturing method of this electronic device may further include the process of peeling the polyimide substrate in which the electronic element etc. were formed from the support body after the board | substrate formation process.

  The present invention has the following configuration.

  1. Polyamic acid characterized by containing a structural unit represented by general formula (1) and a structural unit represented by general formula (2):

R ₁ and R ₂ are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, which may be the same or different, and A in the general formula (2) is a formula The component derived from acid dianhydride, which is any one selected from the structural unit represented by (3), the structural unit represented by formula (4), and the structural unit represented by formula (5) It is.

  2. The molar ratio represented by the number of moles of the structural unit represented by the formula (1) / the number of moles of the structural unit represented by the formula (2) is in the range of 30/70 to 99/1. 2. The polyamic acid according to 1.

  3. The structural unit represented by the general formula (1) is a structural unit represented by the following formula (8), and the structural unit represented by the general formula (2) is represented by the following formula (9). 3. The polyamic acid according to 1 or 2, which is

  The polyamic acid solution containing the polyamic acid in any one of 4.1-3, and an organic solvent.

  5. 5. The polyamic acid solution according to 4, wherein the organic solvent contains at least one selected from an amide solvent, a ketone solvent, an ester solvent, and an ether solvent.

  A polyimide obtained by applying the polyamic acid solution described in 6.4 or 5 to a support.

  7.1 A polyimide obtained by imidizing the polyamic acid according to any one of 1 to 3.

  8). Polyimide comprising the structural unit represented by the general formula (6) and the structural unit represented by the general formula (7):

  R1 and R2 are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, which may be the same or different, and A in the general formula (7) is represented by the formula (3 ), A structural unit represented by formula (4), and a structural unit represented by formula (5), which is a component derived from acid dianhydride. .

  9. The molar ratio represented by the number of moles of the structural unit represented by the formula (6) / the number of moles of the structural unit represented by the formula (7) is in the range of 30/70 to 99/1. 8. The polyimide according to 8.

  10. The structural unit represented by the general formula (6) is a structural unit represented by the following formula (10), and the structural unit represented by the general formula (7) is represented by the following formula (11). The polyimide according to 8 or 9, which is a unit.

  11. The polyimide according to any one of 6 to 10, wherein the light transmittance at a wavelength of 400 nm when the film thickness is 10 μm is 50% or more.

  12 The polyimide according to any one of 6 to 11, wherein a coefficient of thermal expansion at 100 to 300 ° C. when the film thickness is 10 μm is 50 ppm / K or less.

  13. Of the in-plane refractive indexes, nx is the largest and ny is the smallest, and nz is the refractive index in the thickness direction, and nx−ny <0.0010 and (nx + ny) / 2−nz <0. The polyimide according to any one of 6 to 12, which satisfies a relationship of .160.

  14 Glass transition temperature is 250 degreeC or more, The polyimide in any one of 6-13 characterized by the above-mentioned.

  The board | substrate containing the polyimide in any one of 15.6-14.

  The optical material containing the polyimide in any one of 16.6-14.

  The image display apparatus containing the polyimide in any one of 17.6-14.

  Electronic device material containing the polyimide in any one of 18.6-14.

(Evaluation method)
The material characteristic values and the like described in the present specification are obtained by the following evaluation methods.

(1) Molecular Weight of Polyamic Acid The weight average molecular weight (Mw) was determined under the conditions shown in Table 1. The evaluation results are shown in Table 2.

(2) Transmittance of polyimide film Using a UV-Vis near-infrared spectrophotometer (V-650) manufactured by JASCO Corporation, the transmittance of the polyimide film at 200 to 800 nm is measured, and the transmittance at a wavelength of 400 nm is measured. Was used as an index. Further, the wavelength (cutoff wavelength) at which the transmittance was 0.5% or less was also determined.

(3) Coefficient of linear thermal expansion (CTE) of film
The linear thermal expansion coefficient was measured using a TMA120C manufactured by Seiko Electronics Co., Ltd. (sample size: width 3 mm, length 10 mm, film thickness was measured to calculate the cross-sectional area of the film), and the load was 3 gf and 10 ° C./min. Per unit temperature at 100 to 300 ° C. during the second temperature increase when the temperature is once raised from 10 ° C. to 340 ° C., cooled to 10 ° C., and further heated to 340 ° C. at 10 ° C./min. The linear expansion coefficient was determined from the amount of change in strain of the sample.

(4) Glass transition temperature (Tg) of polyimide film
Using TMA120C manufactured by Seiko Electronics Co., Ltd. (sample size: width 3 mm, length 10 mm, film thickness is measured and film cross-sectional area is calculated), the load is 3 g and the temperature is raised to 10-400 ° C. at 10 ° C./min. The amount of change in strain of the film when measured was measured, and the temperature at the inflection point of this amount of change was taken as the glass transition temperature.

(5) Total light transmittance of polyimide film: Measured by Nippon Denshoku Industries Co., Ltd. integrating sphere haze meter 300A according to the method described in JIS K7105-1981.

(6) Haze of polyimide film Measured by a method described in JIS K7105-1981 using an integrating sphere haze meter 300A manufactured by Nippon Denshoku Industries Co., Ltd.

(7) Phase difference measurement A phase difference meter manufactured by Shintech Co., Ltd .: The values of front phase difference and thickness phase difference at a measurement wavelength of 590 nm were measured with OPTIPRO. Using the values, nx-ny and (nx + ny) / 2-nz were calculated. Here, nx, ny, and nz are defined as nx, the smallest one in the in-plane refractive index, ny, and the refractive index in the thickness direction as nz.

(8) Evaluation of glass adhesion The polyamic acid solution was applied to 150 × 150 × 0.7 mm non-alkali glass, dried in air at 60 ° C. for 30 minutes, and then at a rate of 6.5 ° C./min in a nitrogen atmosphere. The temperature was raised to 350 ° C. and further dried at 350 ° C. for 2 hours to form a polyimide film. The film thickness of the polyimide film was set to 10 μm. The state of peeling or floating of the polyimide film from the glass at this time was observed. Observation of peeling or floating of the polyimide film from the glass was carried out by counting the number of foam-like peeled portions from the glass present in the 150 × 150 mm polyimide film. It should be noted that here, as the above-mentioned peeling portions, only those having a long side of 5 mm or more are counted. The evaluation criteria for the adhesion between the support and the polyimide were as follows.
5: No peeling location 4: 1 to 2 peeling locations 3: 3 to 5 peeling locations 2: 5 or more peeling locations or 25% or more of coating area 1 peeling: 50% or more coating area Peeling (Example 1)
<Polymerization of polyamic acid>
7.8 g of trans-1,4-cyclohexanediamine (hereinafter sometimes referred to as CHDA) is placed in a 500 mL glass separable flask equipped with a stirrer made of stainless steel and a nitrogen introduction tube, and polymerized. After dehydrating 120.0 g of dehydrated N, N-dimethylacetamide (hereinafter sometimes referred to as DMAC) as an organic solvent for use, 3,3 ′, 4,4′-biphenyltetracarboxylic acid was added to this solution. 16.0 g of an anhydride (hereinafter sometimes referred to as BPDA) and 6.2 g of 9,9-bis (3,4-dicarboxyphenyl) fluorinated dianhydride (hereinafter sometimes referred to as BPAF) Simultaneously added, heated at 120 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 80 mol% and BPAF: 20 mol% when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 30,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 80%, (nx + ny) / 2-nz was 0.043, CTE was 33 ppm / K, and the glass transition temperature was 367 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polymerized polyamic acid solution was 5. Table 2 shows the evaluation results of the polyimide film.

(Example 2)
<Polymerization of polyamic acid>
After stirring 7.2 kg of CHDA in a 500 mL glass separable flask equipped with a stirrer with a stainless steel stir bar and a nitrogen introduction tube and dehydrating DMAC as an organic solvent for polymerization, this solution was stirred. 11.2 g of BPDA and 11.6 g of BPAF were simultaneously added, heated at 120 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 60 mol% and BPAF: 40 mol%, when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 32,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 82%, (nx + ny) / 2-nz was 0.018, CTE was 46 ppm / K, and the glass transition temperature was 365 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polymerized polyamic acid solution was 5. Table 2 shows the evaluation results of the polyimide film.

(Example 3)
<Polymerization of polyamic acid>
A stirrer equipped with a stirrer made of stainless steel, a nitrogen separable flask equipped with a nitrogen introducing tube, 7.0 g of CHDA were charged, and 120.0 g of dehydrated DMAC as an organic solvent for polymerization was charged and stirred. BPDA 9.0g and BPAF 14.0g were added, and it heated at 120 degreeC for 5 minutes, cooled after that, and stirred at room temperature (23 degreeC) for 5 hours, and polyamic acid was obtained. The charging ratio of each monomer was BPDA: 50 mol% and BPAF: 50 mol%, when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 40,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 82%, (nx + ny) / 2-nz was 0.011, CTE was 47 ppm / K, and the glass transition temperature was 365 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polymerized polyamic acid solution was 5. Table 2 shows the evaluation results of the polyimide film.

Example 4
<Polymerization of polyamic acid>
After putting 6.2 g of CHDA into a 500 mL glass separable flask equipped with a stirrer equipped with a stainless steel stir bar and a nitrogen introduction tube, 170.0 g of DMAC as an organic solvent for polymerization and stirring, BPDA 16 was added to this solution. 0.0 g was added, heated at 100 ° C. for 30 minutes, and then stirred at room temperature for 1 hour. Thereafter, 1.5 g of CHDA was added to this solution, and 6.2 g of BPAF was further added. The mixture was again heated at 100 ° C. for 20 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 80 mol% and BPAF: 20 mol% when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 15 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 45,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution is diluted with DMAC so that the solid content concentration becomes 10%, and the diluted solution is coated on a glass plate with a bar coater, and is heated in air at 60 ° C. for 30 minutes and 350% in a nitrogen atmosphere. It was dried at 0 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 78%, (nx + ny) / 2-nz was 0.073, CTE was 27 ppm / K, and the glass transition temperature was 365 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polyamic acid solution diluted with DMAC so that the solid content concentration becomes 10% was 5. Table 2 shows the evaluation results of the polyimide film.

(Example 5)
<Polymerization of polyamic acid>
A 500 mL glass separable flask equipped with a stirrer equipped with a stainless steel stir bar and a nitrogen inlet tube was charged with 3.5 g of CHDA, and 170.0 g of DMAC was charged as an organic solvent for polymerization and stirred, and then BPDA 9 0.0 g was added, heated at 100 ° C. for 30 minutes, and then stirred at room temperature for 1 hour. Thereafter, 3.5 g of CHDA was added to this solution, and 14.0 g of BPAF was further added, and again heated at 100 ° C. for 20 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 50 mol% and BPAF: 50 mol%, when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 15 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 45,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution is diluted with DMAC so that the solid content concentration becomes 10%, and the diluted solution is coated on a glass plate with a bar coater, and is heated in air at 60 ° C. for 30 minutes and 350% in a nitrogen atmosphere. It was dried at 0 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 79%, (nx + ny) / 2-nz was 0.044, CTE was 36 ppm / K, and the glass transition temperature was 365 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polyamic acid solution diluted with DMAC so that the solid content concentration becomes 10% was 5. Table 2 shows the evaluation results of the polyimide film.

(Example 6)
<Polymerization of polyamic acid>
After stirring 8.3 g of CHDA into a 500 mL glass separable flask equipped with a stirrer with a stainless steel stir bar and a nitrogen introduction tube, and dehydrating 170.0 g of DMAC as an organic solvent for polymerization, this solution was stirred. 21.3 g of BPDA and 0.3 g of BPAF were added, heated at 100 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 99 mol% and BPAF: 1 mol% when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 15 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 50,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution is diluted with DMAC so that the solid content concentration becomes 10%, and the diluted solution is coated on a glass plate with a bar coater, and is heated in air at 60 ° C. for 30 minutes and 350% in a nitrogen atmosphere. It was dried at 0 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 74%, (nx + ny) / 2-nz was 0.120, CTE was 11 ppm / K, and the glass transition temperature was 360 ° C. Moreover, the result of the glass adhesiveness evaluation of the polyimide film performed using the polyamic acid solution diluted with DMAC so that the solid content concentration becomes 10% was 3. Table 2 shows the evaluation results of the polyimide film.

(Example 7)
<Polymerization of polyamic acid>
After stirring 8.3 g of CHDA into a 500 mL glass separable flask equipped with a stirrer with a stainless steel stir bar and a nitrogen introduction tube, and dehydrating 170.0 g of DMAC as an organic solvent for polymerization, this solution was stirred. 20.7 g of BPDA and 1.0 g of BPAF were added, heated at 100 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 97 mol% and BPAF: 3 mol% when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 15 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 50,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution is diluted with DMAC so that the solid content concentration becomes 10%, and the diluted solution is coated on a glass plate with a bar coater, and is heated in air at 60 ° C. for 30 minutes and 350% in a nitrogen atmosphere. It was dried at 0 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 77%, (nx + ny) / 2-nz was 0.120, CTE was 13 ppm / K, and the glass transition temperature was 360 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polyamic acid solution diluted with DMAC so that the solid content concentration becomes 10% was 5. Table 2 shows the evaluation results of the polyimide film.

(Example 8)
<Polymerization of polyamic acid>
A stirrer equipped with a stirrer made of stainless steel, and a 500 mL glass separable flask equipped with a nitrogen inlet tube were charged with 8.2 g of CHDA, and 170.0 g of dehydrated DMAC as an organic solvent for polymerization were charged and stirred. 20.1 g of BPDA and 1.7 g of BPAF were added, heated at 100 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. The charging ratio of each monomer was BPDA: 95 mol% and BPAF: 5 mol% when CHDA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 15 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 50,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution is diluted with DMAC so that the solid content concentration becomes 10%, and the diluted solution is coated on a glass plate with a bar coater, and is heated in air at 60 ° C. for 30 minutes and 350% in a nitrogen atmosphere. It was dried at 0 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 78%, (nx + ny) / 2-nz was 0.115, CTE was 15 ppm / K, and the glass transition temperature was 362 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polyamic acid solution diluted with DMAC so that the solid content concentration becomes 10% was 5. Table 2 shows the evaluation results of the polyimide film.

(Comparative Example 1)
<Polymerization of polyamic acid>
After stirring 8.3 g of CHDA in a 500 mL glass separable flask equipped with a stirrer with a stainless steel stir bar and a nitrogen introduction tube, and adding 120.0 g of dehydrated DMAC as an organic solvent for polymerization, this solution was stirred. 21.6 g of BPDA was added thereto, heated at 120 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 45,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The obtained polyimide film had a transmittance at 400 nm of 70%, (nx + ny) / 2-nz of 0.120, CTE of 11 ppm / K, and a glass transition temperature of 360 ° C. Moreover, the result of the glass adhesiveness evaluation of the polyimide film performed using the polymerized polyamic acid solution was 2. Table 2 shows the evaluation results of the polyimide film.

(Comparative Example 2)
<Polymerization of polyamic acid>
After stirring 8.3 g of CHDA into a 500 mL glass separable flask equipped with a stirrer with a stainless steel stir bar and a nitrogen inlet tube, and stirring 120.0 g of dehydrated NMP as an organic solvent for polymerization, this solution 21.6 g of BPDA was added thereto, heated at 120 ° C. for 5 minutes, then cooled, and stirred at room temperature (23 ° C.) for 5 hours to obtain polyamic acid. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 45,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 49%, (nx + ny) / 2-nz was 0.160, CTE was 7 ppm / K, and the glass transition temperature was 360 ° C. Moreover, the result of the glass adhesiveness evaluation of the polyimide film performed using the polymerized polyamic acid solution was 2. Table 2 shows the evaluation results of the polyimide film.

(Comparative Example 3)
<Polymerization of polyamic acid>
After stirring 6.00 g of CHDA in a 500 mL glass separable flask equipped with a stirrer equipped with a stainless steel stir bar and a nitrogen introduction tube, 120.0 g of dehydrated DMAC as an organic solvent for polymerization was added, and the solution was stirred. BPAF (24.0 g) was added thereto and stirred at room temperature (23 ° C.) for 5 hours to obtain a polyamic acid. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 62,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 83%, (nx + ny) / 2-nz was 0.001, CTE was 52 ppm / K, and the glass transition temperature was 376 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polymerized polyamic acid solution was 5. Table 2 shows the evaluation results of the polyimide film.

(Comparative Example 4)
<Polymerization of polyamic acid>
A stirrer equipped with a stainless steel stir bar and a 500 mL glass separable flask equipped with a nitrogen inlet tube, 13.6 g of 4,4′-diaminodiphenyl ether (hereinafter sometimes referred to as 4,4′-ODA) After adding 120.0 g of dehydrated DMAC as an organic solvent for polymerization and stirring, 3.1 g of BPAF and 13.3 g of pyromellitic acid anhydride (hereinafter sometimes referred to as PMDA) were added to this solution at room temperature. The mixture was stirred at 23 ° C. for 5 hours to obtain polyamic acid. The charging ratio of each monomer was PMDA: 90 mol% and BPAF: 10 mol%, when 4,4′-ODA was 100 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 50,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The obtained polyimide film had a transmittance at 400 nm of 0%, (nx + ny) / 2-nz of 0.048, CTE of 41 ppm / K, and a glass transition temperature of 375 ° C. Moreover, the result of glass adhesion evaluation of the polyimide film performed using the polymerized polyamic acid solution was 5. Table 2 shows the evaluation results of the polyimide film.

(Comparative Example 5)
<Polymerization of polyamic acid>
1.1 g of p-phenylenediamine (hereinafter sometimes referred to as PDA) is placed in a 500 mL glass separable flask equipped with a stirrer made of stainless steel and a nitrogen introduction tube, and is used as an organic solvent for polymerization. After adding 120.0 g of dehydrated DMAC and stirring, PMDA 2.2 g was added to this solution and stirred for 1 hour. Thereafter, 11.9 g of 4,4′-ODA was added and stirred, and 9.1 g of PMDA, 4.1 g of BPDA and 1.6 g of BPAF were further added and stirred at room temperature (23 ° C.) for 5 hours to obtain a polyamic acid. When PDA and 4,4′-ODA were combined to make 100 mol%, PMDA: 75 mol%, BPDA: 20 mol%, and BPAF: 5 mol%. In addition, the preparation density | concentration of the diamine compound and tetracarboxylic dianhydride in this reaction solution was 20 weight% with respect to all the reaction liquids. The weight average molecular weight (Mw) of the polyamic acid was 50,000.

<Preparation of polyimide film>
The polymerized polyamic acid solution was applied on a glass plate with a bar coater and dried in air at 60 ° C. for 30 minutes and in a nitrogen atmosphere at 350 ° C. for 1 hour to obtain a polyimide film having a thickness of 10 μm. The transmittance of the obtained polyimide film at 400 nm was 0%, (nx + ny) / 2-nz was 0.060, CTE was 36 ppm / K, and the glass transition temperature was 357 ° C. Table 2 shows the evaluation results of the polyimide film.

  The polyimides described in Examples 1 to 8 have a transmittance of more than 70% at 400 nm as compared with the polyimides of Comparative Examples 1, 2, 4, and 5, and the transparency is high. It was good as 3 or more, and had a low birefringence value of (nx + ny) / 2−nz <0.120. Furthermore, the polyimides described in Examples 1 to 8 had a low thermal expansion coefficient of 50 ppm / K or less as compared with the polyimide of Comparative Example 3.

  The polyamic acid, the polyimide, and the polyamic acid solution according to the present invention have low birefringence in addition to heat resistance, low thermal expansion, and transparency. In addition, since the adhesion between the support and the polyimide is good, the fields and products in which these characteristics are effective, for example, printed matter, color filters, flexible displays, optical films, liquid crystal display devices, organic It is expected to be used for an image display device such as EL and electronic paper, a 3-D display, a touch panel, a transparent conductive film substrate or a solar cell, and further used as an alternative material for a portion where glass is currently used.

1 Support 2 Polyamic Acid Solution

Claims (18)

Polyamic acid characterized by containing a structural unit represented by general formula (1) and a structural unit represented by general formula (2):

R ₁ and R ₂ are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, and R ₁ and R ₂ may be the same or different, and in the general formula (2) In which A is any one selected from the structural unit represented by formula (3), the structural unit represented by formula (4), and the structural unit represented by formula (5), It is a component derived from things.

The molar ratio represented by the number of moles of the structural unit represented by the formula (1) / the number of moles of the structural unit represented by the formula (2) is in the range of 30/70 to 99/1. The polyamic acid according to claim 1. The structural unit represented by the general formula (1) is a structural unit represented by the following formula (8), and the structural unit represented by the general formula (2) is represented by the following formula (9). The polyamic acid according to claim 1, wherein the polyamic acid is a unit.

  The polyamic acid solution containing the polyamic acid as described in any one of Claims 1-3, and the organic solvent.   The polyamic acid solution according to claim 4, wherein the organic solvent contains at least one selected from an amide solvent, a ketone solvent, an ester solvent, and an ether solvent.   A polyimide obtained by applying the polyamic acid solution according to claim 4 or 5 to a support.   A polyimide obtained by imidizing the polyamic acid according to any one of claims 1 to 3. Polyimide comprising the structural unit represented by the general formula (6) and the structural unit represented by the general formula (7):

R1 and R2 are groups selected from a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, and an alkoxyl group, R1 and R2 may be the same or different, and A in the general formula (7) is a formula The component derived from acid dianhydride, which is any one selected from the structural unit represented by (3), the structural unit represented by formula (4), and the structural unit represented by formula (5) It is.

The molar ratio represented by the number of moles of the structural unit represented by the formula (6) / the number of moles of the structural unit represented by the formula (7) is in the range of 30/70 to 99/1. The polyimide according to claim 8. The structural unit represented by the general formula (6) is a structural unit represented by the following formula (10), and the structural unit represented by the general formula (7) is represented by the following formula (11). The polyimide according to claim 8 or 9, wherein the polyimide is a unit.

  The polyimide according to any one of claims 6 to 10, wherein the light transmittance at a wavelength of 400 nm when the film thickness is 10 µm is 50% or more.   The polyimide according to any one of claims 6 to 11, wherein a thermal expansion coefficient at 100 to 300 ° C when the film thickness is 10 µm is 50 ppm / K or less.   Of the in-plane refractive indexes, nx is the largest and ny is the smallest, and nz is the refractive index in the thickness direction, and nx−ny <0.0010 and (nx + ny) / 2−nz <0. The polyimide according to any one of claims 6 to 12, which satisfies a relationship of .160.   The polyimide according to claim 6, wherein the glass transition temperature is 250 ° C. or higher.   The board | substrate containing the polyimide as described in any one of Claims 6-14.   The optical material containing the polyimide as described in any one of Claims 6-14.   The image display apparatus containing the polyimide as described in any one of Claims 6-14. The electronic device material containing the polyimide as described in any one of Claims 6-14.

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